Valve

ABSTRACT

An esophageal valve has a restriction to allow antegrade passage of swallowed food and controlled retrograde passage of fluid. The restriction comprises an iris having a number of folds.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 11/643,698 filed Dec. 22, 2006 which claims thebenefit of U.S. Provisional Application No. 60/752,881 filed Dec. 23,2005. The present application also claims the benefit of U.S.Provisional Application No. 61/074,384 filed Jun. 20, 2008. The completecontents of all of these are incorporated herein by reference.

INTRODUCTION

The invention relates to devices useful in the treatment of GERD (GastroEsophageal Reflux Disease)

GERD is often caused by a failure of the anti-reflux mechanism. Inhealthy patients the anti-reflux mechanism is comprised of the loweresophageal sphincter (LES) and the “Angle of His,” the angle at whichthe esophagus enters the stomach. These create a valve that preventsduodenal bile, enzymes, and stomach acid from traveling back into theesophagus where they can cause burning and inflammation of sensitiveesophageal tissue.

A surgical treatment, which is often preferred over longtime use ofmedication, is the Nissen fundoplication. In this procedure the upperpart of the stomach is wrapped around the LES (lower esophagealsphincter) to strengthen the sphincter and prevent acid reflux and torepair a hiatal hernia. The procedure is usually carried outlaparoscopically.

In 2000 the U.S. Food and Drug Administration (FDA) approved twoendoscopic devices to treat chronic heartburn. In one system stitchesare put in the LES to create pleats to strengthen the muscle. Another,the Stretta Procedure, uses electrodes to apply radio frequency energyto the LES. The long-term outcomes of both procedures compared to aNissen fundoplication are still being determined.

The NDO Surgical Plicator is also used for endoscopic GERD treatment.The Plicator creates a plication, or fold, of tissue near thegastroesophageal junction, and fixates the plication with a suture-basedimplant. The Plicator is currently marketed by NDO Surgical, Inc.

STATEMENTS OF INVENTION

According to the invention there is provided an esophageal valve havinga restriction to allow antegrade passage of swallowed food andcontrolled retrograde passage of fluid, the restriction comprising airis having a number of folds.

In one embodiment the valve is adapted to be opened when differentforces are applied in the antegrade and retrograde directions.

In one case the valve is adapted to open in the antegrade direction inresponse to antegrade forces and to open in the retrograde direction inresponse to retrograde forces, the retrograde force required to open thevalve being substantially greater than the antegrade force required toopen the valve.

In one embodiment the iris is formed from a tubular precursor, the endsof which are oppositely rotated. The precursor may be folded as the endsare oppositely rotated. In one case the precursor is generallycylindrical. In one case the precursor is generally of hourglass shape.

In one embodiment the restriction comprises at least three folds.

In one case the valve has means to set the differential forces requiredto open the valve.

The valve may comprise a stop to restrict the opening of the valve inone direction.

In one case the valve comprises strengthening means to restrict theopening of the valve in one direction.

In one embodiment the valve comprises a support for the iris.

In one case the tubular iris is attached to the support. The attachmentsmay be arranged such that the valve will open in response to differentforces applied in the antegrade and in the retrograde directions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the followingdescription thereof given by way of example only, in which:

FIGS. 1 to 8 illustrate a valve of the invention in variousconfigurations;

FIG. 9 is an isometric view of a valve device according to theinvention;

FIG. 10 is a cross sectional view of the device of FIG. 9;

FIG. 11 is a plan view of a valve of with four folds;

FIG. 12 is a plan view of a valve with five folds;

FIG. 13 is a plan view illustrating the operation of the valve;

FIGS. 14 and 15 are cross sectional views of the valve in use; and

FIG. 16 is a cross sectional view of the valve in use.

DETAILED DESCRIPTION

The invention is a prosthetic esophageal valve, which prevents refluxfrom entering into the esophagus. The valve is specifically designed toallow swallowed food to pass distally through it and also to allowretrograde flow of liquid and gasses proximally during belching orvomiting.

FIGS. 1 to 8 illustrate a valve 1 in various configurations. The valve 1comprises a sleeve 5 which is twistable to move the sleeve 5 between anopen configuration (FIGS. 1 and 2) in which a lumen 6 is open, and asealed configuration (FIGS. 7 and 8) in which the lumen is closed.

The implantable sleeve 5 could have an “hourglass” shape, as illustratedin FIGS. 1 to 8. This shape would enable the device to be located andsecured at the oesophageal sphincter 25. In addition the device can betwisted in-situ by the clinician to tailor the elasticity of the orificecreated. The sleeve 5 could be held in place either by sutures or by anadhesive.

FIGS. 1 to 8 illustrate the sleeve 5 designed as a sphincter implantwith adjustable opening tightness.

Referring to FIGS. 9 to 16, in this case the middle of the valve has arestriction 10 that controls flow in both directions. The restriction 10is formed through a series of folds 11 in the lumen of the valve, whichare created by simultaneously rotating and folding a precursor asdescribed above with reference to FIGS. 1 to 8.

The precursor component can be a straight tube or an hourglass shapedtube with an open lumen.

Additionally, the tube can have specific internal profiles such ashelical ribs or protrusions. The proximal and distal opening forces canbe varied by changing the internal profile of the valve or the conicalangle at either end of the valve. The valve may be mounted to asemi-rigid support 20 such as a braided plastic stent. In this casethere is a proximal mounting 26 and a distal mounting as illustratedparticularly in FIG. 10. The degree of attachment may be varied toinfluence the characteristics of the valve. For example, the distalattachment 27 may be adapted to facilitate opening in response to apre-determined retrograde force P₂ which will facilitate belching orvomiting. Similarly, the proximal attachment 26 may be adapted tofacilitate opening in response to a pre-determined antegrade force P₁.

The restriction can be created by rotating the ends of the tubularprecursor contrary to each other either clockwise or anticlockwise. Thishas the effect of creating an internal iris in the centre of the rotatedtube. The iris thus created has a number of folds or wings, which arepredetermined prior to rotation. The angle of rotation can be between 15and 200°. The angle of rotation can be used to vary the force to beapplied to pass through.

In addition, during the rotation of the tube it naturally foreshortens.The foreshortening effect can be controlled by applying longitudinalcompression or tension.

When the target angle of rotation, number of folds and degree offoreshortening is achieved the iris can be locked into it's desiredconfiguration by externally connecting it to a supporting structure 20.The restriction can be made from three or more folds. The helical angleof the internal ribs can be between 10 and 90° to the vertical.

The valve functions as a conformable iris in which the opening force canbe predetermined through its geometric properties.

It is possible to make the valve open with different forces in theproximal and distal directions. For example, a re-inforcing ring may beplaced at one side of the valve. This functions as a physical stop toreduce the freedom of movement of the iris wings in one direction.Alternatively or additionally the opening characteristics in response toantegrade and retrograde flow can be altered by providing additionallayers or thicknesses of material at appropriate locations.

The conical sections 3, 4 act as a means to direct food through thelumen rather than around the outside of the device whereas the narrowrestriction 2 in the middle of the valve functions as a means ofpreventing flow.

The force provided by the valve to restrict flow is dependent on anumber of factors including:

the degree of restriction in the centre of the valve;

the angle or curvature between the end of the device and the centralrestriction;

whether the angle (or curvature) of the proximal and distal ends of thedevice are the same. Different angles will create different degrees ofrestriction in the proximal and distal directions;

the ‘pass through’ force can also be manipulated by changing thematerial properties from which the valve is made; and

the properties of the valve will also be influenced by the externalforces placed upon it by the natural movement and pressure of theesophagus. This external force may augment the functioning of the valveby contributing to the degree of restriction.

The angle that the proximal end of the device makes with the restrictioncan be between 10 and 90° to the horizontal.

The luminal diameter of the restriction in the centre of the valve canbe between 0 and 20 mm.

The elongation of the material used to construct the restriction can bebetween 50 and 3000%

The tensile strength of the material used to construct the restrictioncan be between 0.01 and 5 N/mm².

In order to facilitate the normal passage of food in the esophagus therestriction is capable of opening, in the proximal direction, with anaxial force of between 50 and 100 g.

In order to facilitate normal belching and vomiting the restriction iscapable of opening, in the distal direction, with a pressure of between200 and 500 mmH₂O.

This design creates the optimum valve conditions while positioned in thelumen of the esophagus. Previous approaches have required devices to beplaced either on the outside of the esophagus or under the mucosalsurface tissue of the esophagus. Thus the current invention circumventsthe need for invasive procedures.

The valve allows retrograde opening at precisely defined pressures.

Because the valve does not invert to facilitate belching and vomiting itdoes not have to reorient itself periodically.

Many variations of valve can be produced to treat varying severity ofdisease.

The device can also be made in a very low profile fashion to facilitateits crimping and subsequent delivery.

The valve of the invention requires very low actuation pressure. It canfunction asymmetrically to mimic the various bodily functions in theesophagus.

The valve may be of any suitable biocompatible materials that havecharacteristics as follows. The materials used for the production ofthis valve should have a % elongation between 50% and 3000%.Additionally the material could have an antimicrobial action to preventcolonisation when in-vivo. Additionally the material can be elastic orviscoelastic and can optionally be an open cell foam. The density of thematerial should be between 0.1 g/cm³ to 1.5 g/cm3.

The valve of the invention may be used to treat gastroesophageal refluxdisease.

The invention is not limited to the embodiments hereinbefore described,which may be varied in detail.

1. An esophageal valve having a restriction to allow antegrade passageof swallowed food and controlled retrograde passage of fluid, therestriction comprising an iris having a number of folds.
 2. A valve asclaimed in claim 1 wherein the valve is adapted to be opened whendifferent forces are applied in the antegrade and retrograde directions.3. A valve as claimed in claim 2 wherein the valve is adapted to open inthe antegrade direction in response to antegrade forces and to open inthe retrograde direction in response to retrograde forces, theretrograde force required to open the valve being substantially greaterthan the antegrade force required to open the valve.
 4. A valve asclaimed in claim 1 wherein the iris is formed from a tubular precursor,the ends of which are oppositely rotated.
 5. A valve as claimed in claim4 wherein the precursor is folded as the ends are oppositely rotated. 6.A valve as claimed in claim 4 wherein the precursor is generallycylindrical.
 7. A valve as claimed in claim 4 wherein the precursor isgenerally of hourglass shape.
 8. A valve as claimed in claim 1 whereinthe restriction comprises at least three folds.
 9. A valve as claimed inclaim 1 wherein the valve has means to set the differential forcesrequired to open the valve.
 10. A valve as claimed in claim 9 whereinthe valve comprises a stop to restrict the opening of the valve in onedirection.
 11. A valve as claimed in claim 9 comprising strengtheningmeans to restrict the opening of the valve in one direction.
 12. A valveas claimed in claim 1 comprising a support for the iris.
 13. A valve asclaimed in claim 12 wherein the tubular iris is attached to the support.14. A valve as claimed in claim 13 wherein a distal end of the tubulariris is attached to the support and a proximal end of the tubular irisis attached to the support.
 15. A valve as claimed in claim 14 whereinthe attachments are arranged such that the valve will open in responseto different forces applied in the antegrade and in the retrogradedirections.